Anti-piracy message targets downloaders

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A pair of New York inventors believe they can thwart music
pirates by secretly burying an anti-piracy warning in a track,
which is disinterred if the copyright has been abused, New
Scientist reports.

The warning - for instance, a voice from a record company boss,
berating the user for piracy - exploits the fact that the tones of
a musical instrument consist of a complex pattern of
randomly-phased harmonics.

Inventors Mark Bocko and Zeljko Ignjatovic tweaked a few
harmonics to shift out of the pattern and then used those shifts to
convey a 20-kilobit speech message.

Their patented idea is to incorporate a software decoder in
file-sharing applications which encourage mass copying and are the
bane of the music industry today.

The decoder would detect the telltale phase shifts and convert
them into the warning message, causing them to boom out through
loudspeakers or headphones, the British weekly reports in next
Saturday's issue.

For legitimate listeners, though, the digital shifts are so
small that there is no difference at all in the perception of the
music.

Previous attempts by researchers to bury anti-piracy signals in
copyrighted music and films have run into counter-measures by
hackers, who filter out the message, and also compatibility
problems in players.